Chemistry Notes

1.The amount of CO₂ in the atmosphere has increased in the last 100 years.Give one reason why this has happened.

Burning of fossil fuels.

1.Explain how carbon dioxide is added to and removed from today’s atmosphere (6)

Carbon dioxide is added to the atmosphere by volcanic activity – gases burnt out in eruption, burning fossil fuels – because they contain carbon and deforestation – because less tress to absorb carbon dioxide. Carbon dioxide is removed from the atmosphere by dissolving in oceans – because carbon dioxide is soluble and photosynthesis – because carbon dioxide is converted to sugars in plants. Relative amounts added and removed determine whether the amount of carbon dioxide in atmosphere rises, falls or remains the same.

1.Sometime after the early atmosphere had been formed, oceans appeared on the earth’s surface.State how these oceans were formed (1)

Water vapour

2.State how the formation of the oceans caused reduction (1)

Carbon dioxide dissolved.

3.Describe the process that has caused the increase of oxygen in our atmosphere today (2)

Plants produce oxygen by photosynthesis.

1.Explain why it is difficult to be precise about the composition of the earths early atmosphere (2)

Nobody was there so there are no written records.

As the earth cooled, oceans formed.How did this affect the composition of the atmosphere? (1)

Lowered the amount of carbon dioxide.

The first plants appeared about 400 million years ago.Explain how the growth of these plants affected the composition of the atmosphere (2)

Photosynthesis in plants absorbed carbon dioxide.

State another cause of increasing amounts of carbon dioxide in the atmosphere (1)

Deforestation.

1.Explain why some people are concerned about the increase in the amount of carbon dioxide in the atmosphere (2)

Greenhouse gases may lead to increase in global warming.

1.Explain why the water in the test tube rose during the experiment (2)

The iron reacts with the oxygen in the air, so oxygen is removed from the air.

Explain how the use of fossil fuels affects the composition of the atm (2)

Burning fossil fuels removes oxygen in the atmosphere

Metal carbonates

1.How is the calcium carbonate turned into calcium oxide? (1)

Heat.

State on observation that can be made when water is added to calcium oxide? (1)

Steam forms.

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1.Use the data to explain which of the metal carbonates seems to be the most thermally stable (2)

Barium carbonate, least mass loss.

Equation for the decomposition of copper carbonate to copper oxide and carbon dioxide.

CuCO3 → CuO + CO2

Describe how the solid calcium hydroxide could be used to test for carbon dioxide (2)